Why do roaches flip over on their backsides when they die? I sprayed RAID into a hole in my wall the other?

roaches (and most other insects) are top heavy since they have bulky bodies and thin, long legs. When they die, their leg muscles contract, pulling them beneath the body causing it to tip over. It is possible for the dead animal to remain on its side, but usually with death comes involuntary twitching of the muscles causing the occurrence of ending up on its back more likely. Also if the roach dies while on a wall, it will fall and most likely end up on its back as well.